Ruby Benchmark: Counting the number of lines of a file

line_count_benchmark.rb

# gem install benchmark-ips

require "benchmark/ips"

path = "lib/rubycritic/cli/options.rb"

Benchmark.ips do |x|
  x.report("read + each_line") { File.read(path).each_line.count }

  x.report("open + each_line") { File.open(path, "r").each_line.count }

  x.report("open + readlines") { File.open(path, "r").readlines.length }

  x.report("foreach + count") { File.foreach(path).count }

  x.report("foreach + inject") { File.foreach(path).inject(0) {|count, line| count+1} }

  x.report("foreach") { count = 0; File.foreach(path) { count+=1}; count }

  x.report("wc") { `wc -l < "#{path}"`.to_i }

  x.compare!
end

results

Calculating -------------------------------------
    read + each_line     4.272k i/100ms
    open + each_line     4.075k i/100ms
    open + readlines     4.050k i/100ms
     foreach + count     3.569k i/100ms
    foreach + inject     2.979k i/100ms
             foreach     3.397k i/100ms
                  wc    26.000  i/100ms
-------------------------------------------------
    read + each_line     44.535k (± 2.7%) i/s -    226.416k
    open + each_line     42.232k (± 2.7%) i/s -    211.900k
    open + readlines     41.585k (± 5.8%) i/s -    210.600k
     foreach + count     38.254k (± 1.1%) i/s -    192.726k
    foreach + inject     31.478k (± 0.8%) i/s -    157.887k
             foreach     35.819k (± 3.2%) i/s -    180.041k
                  wc    260.809  (± 3.8%) i/s -      1.326k

Comparison:
    read + each_line:    44534.7 i/s
    open + each_line:    42232.2 i/s - 1.05x slower
    open + readlines:    41584.8 i/s - 1.07x slower
     foreach + count:    38254.1 i/s - 1.16x slower
             foreach:    35818.6 i/s - 1.24x slower
    foreach + inject:    31478.2 i/s - 1.41x slower
                  wc:      260.8 i/s - 170.76x slower